1. Field of the Invention
The present invention relates to a breather structure for an internal combustion engine wherein a breather hole for mitigating the pressure in an engine body is provided in the engine body.
2. Description of Background Art
A technology is known for preventing the oil stored in an engine body of an internal combustion engine mounted on a motorcycle, from flowing out through a breather hole in the event that the motorcycle overturns. See, for example, JP-A No. H5-171915. Further, a technology is known that is designed for preventing oil from flowing out from a breather pipe connected to an engine body of an internal combustion engine mounted on a small planing boat in the event that the boat overturns. See, for example, JP-A No. 2003-54484.
In the technology in the aforementioned JP-A No. H5-171915, a breather hole opening to a breather chamber extending in a vehicle width direction and a pressure hole connecting a crankcase and the breather chamber are provided in the engine body to be spaced in the vehicle width direction wherein at least one of the breather hole and the pressure hole is placed above the surface of the oil in the crankcase in the event that the motorcycle overturns. This results in limiting the freedom in placement of the breather hole. Further, in the technology disclosed in JP-A No. 2003-54484, a breather box is placed above a connecting portion of the breather pipe to the engine body, and an intermediate portion of the breather pipe connecting the engine body and the breather box is placed lower than the connecting portion of the breather pipe to the engine body. This results in limiting the freedom in placement of the connecting portion of the breather pipe to the engine body.